Collaborative Research: Two-Dimensional Substrates to Study and Control the Atomic-Scale Structure of Metal Nanoclusters

非技术综述：附着在载体材料表面的含有有限数量的金属原子的纳米团簇(NCs)在能源技术中的应用中起着至关重要的作用。二维衬底为研究NCS提供了一个独特的平台，因为它们的大而明确的表面没有悬挂键，并且电子的散射最小，这使得NCS能够以原子分辨率成像。这项研究的目标是采用自洽的、理论和实验相结合的方法来研究支撑的金属NC，以及这些NC如何适应衬底的变化。理论计算基于经典和量子理论，结合进化算法，而实验方法依赖于电子显微镜来确定纳米级的结构。在教育方面，拟议的研究将成为研究生和本科生在纳米尺度上学习材料发现的跨学科平台。鉴于新材料将对日常生活和国家经济产生重大影响，这项工作将通过开发新的课程组件和新颖的教育模块，以及为大学预科和高中生开展推广活动，加强匹兹堡大学和芝加哥伊利诺伊大学的材料教育。技术概述二维(2D)衬底上支撑的亚纳米团簇的原子结构在科学上是一个具有挑战性的领域，而且在很大程度上还没有被探索。完成后，这项工作将确定2D衬底的变化如何影响所支持的NC的原子结构。利用原子力场和密度泛函理论，利用遗传算法对原子结构进行了预测，并用像差校正的扫描电子显微镜进行了验证。值得注意的是，将实验结果与理论预测相关联将促进对2D衬底上负载金属的基本理解，这可能是使用这种衬底作为在原子尺度上控制金属团簇结构的手段的基础。拟议的研究工作将进一步与教育工作相结合，在教育工作中，研究生和本科生将接受多学科研究培训。在拟议的研究中，将使用专门的努力和资源来招募和支持代表性不足的学生(女性、非裔美国人、拉美裔美国人和第一代学生)。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non Technical Summary Nanoscale clusters (NCs) containing a finite number of metal atoms and attached to the surfaces of support materials play a pivotal role for applications in energy technologies. Two-dimensional substrates offer a unique platform to study NCs owing to their large and well-defined surfaces with no dangling bonds, and minimal scattering of electrons, which allows for imaging of NCs with atomic resolution. The goal of this research is to employ a self-consistent, combined theoretical and experimental approach to study supported metal NCs, and how these adapt by substrate variations. The theoretical calculations are based on classical and quantum theories in conjunction with evolutionary algorithms, while as the experimental approach relies on electron microscopy to determine the structure at the nanoscale. Educationally, the proposed research will serve as an interdisciplinary platform for graduate and undergraduate students to learn about materials discovery at the nanoscale. Given the significant impact that novel materials will have on much of daily life and the national economy, this work will strengthen materials education at the University of Pittsburgh and the University of Illinois at Chicago via developing new course components and novel education modules, as well as conducting outreach activities for pre-college and high school students.Technical Summary The atomic structure of supported sub-nanometer clusters on two-dimensional (2D) substrates is a scientifically challenging and largely unexplored field of study. Upon completion, this work will determine how variations in 2D substrates can impact the atomic structure of supported NCs. The atomic structures are predicted using a genetic algorithm utilizing atomistic force fields and density functional theory, which are then validated using aberration-corrected scanning transmission electron microscopy. Significantly, correlating experimental results with theoretical predictions will lead to advances in the fundamental understanding of supported metals on 2D substrates that could be the basis for using such substrates as a means to control the structure of the metal clusters at the atomic scale. The proposed research efforts will be further integrated with educational efforts where graduate and undergraduate students will be trained in multidisciplinary research. Dedicated effort and resources will be used to recruit and support underrepresented students (women, African-Americans, Hispanics, and first-generation) in the proposed research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.